Editing IBM PS/2 Model 80 Troubleshooting Guide

[[File:IBM PS-2 Model 80 (photo).jpg|thumb|right|300px|IBM PS/2 Model 80. Source: Wikimedia Commons.]]
This guide documents fault diagnosis for the '''[[IBM PS/2 Model 80]]''' (machine type 8580, all submodels). The Model 80 shares its POST architecture with the [[IBM PS/2 Model 70]] (same planar family) but has 8-slot MCA, server-class ESDI configurations and Type 1 / Type 2 planar differences that affect troubleshooting.

== Reference Diskette and Diagnostics ==

The Model 80 requires the '''Model 80-specific Reference Diskette'''. The Type 1 planar (8580-041 / 071 / 111 / 311) uses one Reference Diskette image; the Type 2 planar (8580-A21 / A31) uses a different Reference Diskette image. Use of the wrong Reference Diskette will refuse to boot or will mis-configure the planar.

Boot Options:

* '''F1''' — boot the Reference Diskette.
* '''Ctrl-A''' from the Reference Diskette menu — Advanced Diagnostics.

== POST Sequence ==

The Model 80 POST runs in this order:

# Reset; CPU register check (80386 includes paging and protected mode tests).
# ROM checksum.
# CMOS / RTC battery check.
# Planar RAM count.
# Onboard VGA initialisation.
# Floppy controller and drive seek.
# MCA adapter ID scan (each card returns a 16-bit ID; up to 8 cards).
# ADF lookup against CMOS configuration record.
# ESDI controller initialisation.
# Boot device selection.

== Beep Codes ==

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Model 80 beep codes'''
! Beeps !! Meaning
|-
| 1 short || POST passed; normal boot.
|-
| 2 short || Configuration error; numeric error on screen.
|-
| 1 long, 1 short || Planar fault.
|-
| 1 long, 2 short || Display adapter fault.
|-
| Continuous || Power supply or planar fault.
|-
| None, no display || Planar or PSU fault before video init.
|}

== Numeric POST Codes ==

The Model 80 shares the same 1xx–104xx code families with the Model 70. Codes that are identical to the Model 70 are summarised here; refer to [[IBM PS/2 Model 70 Troubleshooting Guide]] for the complete tables.

=== 1xx — Planar / System Board ===

Same as Model 70. Key codes:

* '''104''' — Protected-mode failure. Often planar SMD cap leakage near the CPU.
* '''114''' — Paging test failure (80386-specific).
* '''161 / 162 / 163''' — CMOS / RTC battery cluster. Replace DS12887.
* '''164''' — Memory size mis-match with CMOS. Run SETUP.
* '''165''' — MCA adapter ID mismatch. Run Auto Configuration. '''More common on Model 80 than Model 70 due to higher card count.'''
* '''166''' — MCA arbitration failure.

=== 2xx — RAM ===

Same as Model 70. The Type 2 planar (8580-A21 / A31) is more particular about SIMM speed and rejects slower SIMMs with a 201 / 225 cluster.

=== 3xx — Keyboard ===

Same as Model 70.

=== 6xx — Floppy Drive ===

Same as Model 70.

=== 8xx — Math Coprocessor ===

The Model 80 supports the optional '''80387DX''' coprocessor.

* '''801''' — Coprocessor test failed.

=== 104xx — ESDI Fixed Disk Adapter/A ===

The Model 80 uses the '''IBM ESDI Fixed Disk Adapter/A''' (or its later revision for the larger 314 MB drives) for the hard drive subsystem. The 104xx error family is the same as on the Model 70.

See [[IBM PS/2 Model 60 Troubleshooting Guide]] for the complete 104xx code table.

Server configurations (8580-311 / A31) with two ESDI drives use:

* '''10480''' — Drive 0 fatal error.
* '''10481''' — Drive 1 fatal error.

This is the only place the second drive is called out separately in POST.

=== 24xx — Onboard VGA ===

Same as Model 70:

* '''2401''' — Onboard VGA POST failure.
* '''2402''' — VGA video memory failure.
* '''2410''' — Planar VGA card failure.

A 24xx on a Model 80 is one of the more common SMD electrolyte leak symptoms.

== SMD Electrolyte Leak Diagnostic Workflow ==

The Model 80 planar's SMD electrolytic capacitors are the leading cause of "the Model 80 won't POST" complaints. The same symptoms apply as on the Model 70:

* '''104''' (protected mode) — SMD leak near the CPU.
* '''201''' (memory) — SMD leak near the SIMM controller.
* '''2401''' (VGA) — SMD leak near the VGA chip.
* Random reboots — SMD leak on a bus signal.
* No POST at all — SMD leak shorting a power rail.

If a Model 80 is exhibiting any persistent or intermittent POST fault, '''inspect the planar for SMD electrolyte leakage before any other diagnosis'''. Read [[IBM PS/2 Model 80 Capacitor Replacement Guide]] for the recap procedure.

The Model 80 has 40–50 SMD electrolytics (more than the Model 70's ~36–40) because of the larger MCA bus controller and server-class memory subsystem. The likelihood of at least one SMD cap leaking is correspondingly higher.

== MCA-Specific Faults ==

=== 165 Card-ID Mismatch ===

With 7 × 32-bit MCA slots typically populated to 3–5 cards in a Model 80 (vs. 1–2 on a Model 70), the 165 fault is more common. Causes and fix are the same as on the Model 70:

# Boot the Reference Diskette.
# Select '''Set Configuration → Run Auto Configuration'''.
# Insert option diskettes as prompted.
# Save and reboot.

If 165 persists, reseat every card, clean edge fingers, and bring the card complement up one at a time to isolate the faulty card.

=== 8-bit Slot Limitations ===

The Model 80 has '''one 8-bit MCA slot''' (in addition to seven 32-bit slots). The 8-bit slot accepts 8-bit MCA cards (rare) but is also wired to accept 16-bit MCA cards in 8-bit mode. Do '''not''' plug a 32-bit MCA card into the 8-bit slot — it will not POST and may damage the card.

== Type 1 vs Type 2 Planar Differences ==

Diagnosing a fault requires knowing which planar is in front of you:

{| class="wikitable styled-table" style="width:100%; text-align:center;"
|+'''Type 1 vs Type 2 planar — identification'''
! Marker !! Type 1 (16 / 20 MHz) !! Type 2 (25 MHz)
|-
| Submodels || 041, 071, 111, 311 || A21, A31
|-
| CPU speed || 16 or 20 MHz || 25 MHz
|-
| SIMM speed required || 80 ns or faster || 70 ns or faster
|-
| Reference Diskette || Type 1 || Type 2
|}

A Type 1 Reference Diskette booted on a Type 2 planar will report incorrect memory configuration and may refuse to complete SETUP. A Type 2 Reference Diskette on a Type 1 planar will also misconfigure.

== ECA Recalls and Service Bulletins ==

The Model 80 was affected by several Engineering Change Authorisation (ECA) bulletins:

* '''ECA 087''' — Reference Diskette compatibility update for newer MCA cards.
* '''ECA 092''' — Planar fix for one revision of the Model 80.
* '''ECA 117''' — ESDI controller firmware update (particularly relevant on the 314 MB ESDI drive configurations).

These ECAs apply only to specific FRU part numbers; check the planar / card FRU against the bulletin before applying.

== PSU Faults ==

Symptoms and diagnosis:

* '''Dead — no fans, no power''': Bulk capacitor or mains rectifier; PSU recap required. See [[IBM PS/2 Model 80 Capacitor Replacement Guide]].
* '''Fans spin briefly, then click-retry''': Power Good not asserted in 150 ms. Could be PSU fold-back or shorted planar tantalum / leaked SMD electrolyte.
* '''Boots cold, fails when warm''': Secondary electrolytics aged.
* '''Audible whine, smell of fish''': RIFA X2 cap is venting.
* '''Rails low/high''': PSU feedback path issue.

The 225 W PSU on the Model 80 has comfortable headroom for the 80386DX, the planar VGA and up to 7 MCA cards. A rail sag on a properly-functioning Model 80 PSU usually indicates an aged secondary electrolytic.

== Drive Stiction ==

ESDI drives in the Model 80, particularly the 314 MB drives, are notoriously prone to spindle stiction after long storage. Same field fix as on the Model 60 / 70:

* Power off.
* Open the chassis. Locate the drive.
* Gently rotate the drive case 45–90° around its spindle axis in both directions to free the heads.
* Re-install. Power on.

The 314 MB drive is full-height and heavier than the smaller ESDI drives; handle with care during the stiction-freeing procedure.

After the drive boots, '''immediately''' image its contents to a modern disk image file. The drive cannot be trusted to spin up reliably again.

== Server Configuration-Specific Faults ==

The 8580-311 and 8580-A31 ship with the 314 MB ESDI drive in the top bay and a smaller (1.44 MB) floppy in Bay 2. Things to know:

* The 314 MB ESDI drive draws more startup current than the 70 / 115 MB drives. PSU rail sag at boot is more pronounced; if the 225 W PSU has aged caps, the 314 MB submodels will exhibit boot failures before the 111 / 071 / 041 submodels do.
* The dual-drive 8580-311 / A31 configurations require the ESDI controller card to be configured for two drives (via the Reference Diskette SETUP).
* Novell NetWare on the 8580-311 / A31 is sensitive to drive timing — aged ESDI controller caps produce NetWare-side errors that look like volume corruption.

== Keyboard / Mouse Faults ==

Same as Model 70:

* '''301''': Keyboard or mouse in the wrong port.
* '''305''': +5 V fuse on planar blown.
* '''365''': PS/2 mouse fault.

== Memory Faults ==

* '''201''' with planar-range address: Planar SIMM failure. Identify the failing bank from the address.
* '''201''' with MCA Memory Adapter address: Memory adapter card failure.
* '''215 / 216''': MCA Memory Adapter configuration error.
* '''225''' on a Type 2 planar: SIMMs too slow.

== When to Suspect the Planar ==

* 1xx errors that persist after CMOS battery replacement and Auto Configuration.
* No video and no beeps after PSU verified known-good.
* Repeated 165 errors after every card removed and reseated.
* '''Any''' visible SMD electrolyte leak.

The Model 80's larger SMD cap count makes planar leakage statistically more likely than on the Model 70.

== Diagnostic Workflow ==

# Visually inspect planar for SMD electrolyte leak first. If found, do not power on.
# Confirm Type 1 vs Type 2 planar and use correct Reference Diskette.
# Power on. Listen for beep.
# Note POST screen — any leading numeric code.
# If 161/162/163 cluster — replace DS12887 module.
# If 165 — run Auto Configuration; cards reseated.
# If 104xx — verify drive type in CMOS; reseat drive cable; consider stiction; consider controller cap failure.
# If 24xx — planar VGA fault, often SMD electrolyte leak.
# If 104 — 80386 protected mode fault, often SMD electrolyte leak near CPU.
# If no beep and no video — PSU first (rail check), then planar SMD inspection.
# Run Advanced Diagnostics (Ctrl-A) once basic POST passes.

== ⚠️ Power-supply RIFA capacitor and tantalum shorts ==

Two age-related failures are near-universal on this era of IBM hardware:

* '''RIFA mains-filter capacitors''' in the power supply are metallised-paper parts that crack and fail '''short''' with age, producing acrid smoke shortly after power-on. Replace them pre-emptively with modern X2-class parts.<ref name="ibm_rifa">[https://www.minuszerodegrees.net/failure.htm minuszerodegrees.net — IBM failure symptoms]; [https://www.classic-computers.org.nz/blog/2010-11-04-restoring-an-IBM-xt.htm Repairing and Restoring an IBM XT]; and [https://retrorepairsandrefurbs.com/2025/05/15/1983-ibm-pc-5160-xt-power-supply-rebuild-modifications/ Adam's Vintage Computer Restorations]. Source for the RIFA mains-filter capacitor failing short (smoke) and the tantalum capacitors failing short and preventing the PSU from firing.</ref>
* '''Tantalum capacitors''' on the planar (system board) and on ISA cards fail short with age. A shorted tantalum will '''prevent the power supply from starting''' (dead machine, PSU protection latched) &mdash; look for a cracked or discoloured tantalum and lift suspect ones to find the short.<ref name="ibm_rifa">[https://www.minuszerodegrees.net/failure.htm minuszerodegrees.net — IBM failure symptoms]; [https://www.classic-computers.org.nz/blog/2010-11-04-restoring-an-IBM-xt.htm Repairing and Restoring an IBM XT]; and [https://retrorepairsandrefurbs.com/2025/05/15/1983-ibm-pc-5160-xt-power-supply-rebuild-modifications/ Adam's Vintage Computer Restorations]. Source for the RIFA mains-filter capacitor failing short (smoke) and the tantalum capacitors failing short and preventing the PSU from firing.</ref>

IBM PC/XT switching supplies also need a '''minimum load''' to start, so a bare supply on the bench may not run without a dummy load.<ref name="ibm_rifa">[https://www.minuszerodegrees.net/failure.htm minuszerodegrees.net — IBM failure symptoms]; [https://www.classic-computers.org.nz/blog/2010-11-04-restoring-an-IBM-xt.htm Repairing and Restoring an IBM XT]; and [https://retrorepairsandrefurbs.com/2025/05/15/1983-ibm-pc-5160-xt-power-supply-rebuild-modifications/ Adam's Vintage Computer Restorations]. Source for the RIFA mains-filter capacitor failing short (smoke) and the tantalum capacitors failing short and preventing the PSU from firing.</ref>

== ⚠️ CMOS / RTC battery ==

This machine keeps its configuration in battery-backed CMOS, and the battery is a common failure. On AT-class boards the clock/CMOS is often a '''Dallas DS1287/DS12887''' module with the cell sealed inside; it lasts about ten years and then dies, giving '''161 / 163''' CMOS and clock errors at POST (and sometimes spurious floppy-drive errors). PS/2 planars use a rechargeable barrel or pack battery that '''leaks''' and corrodes the board. Replace a dead Dallas module (or rework it with an external coin cell), and on a leaking planar battery remove it and clean the corrosion before it eats the traces.<ref name="ibm_batt">[https://www.classic-computers.org.nz/blog/2009-10-10-renovating-a-dallas-battery-chip.htm Fixing a Flat Dallas DS1287 RTC], Classic Computers; and [https://www.ardent-tool.com/misc/Dallas_Rework.html Reworking Dallas RTC Modules], Ardent Tool. Source for the Dallas DS1287/DS12887 internal-battery death (161/163 CMOS errors) and the leaking planar battery.</ref>

== References ==

<references />

== Related Pages ==

* [[IBM PS/2 Model 80]]
* [[IBM PS/2 Model 80 Maintenance Guide]]
* [[IBM PS/2 Model 80 Capacitor Replacement Guide]]
* [[IBM PS/2 Model 70 Troubleshooting Guide]] — desktop sibling, same planar family
* [[IBM PS/2 Model 60 Troubleshooting Guide]] — same tower chassis

== References ==

* [https://www.ardent-tool.com/trouble/ps2error.html PS/2 Error Codes — Ardent Tool of Capitalism]. Source for the 1xx–104xx error code tables.
* [https://www.ardent-tool.com/qtechinfo/GJAN-43VS3S.html IBM PS/2 Model 80 — Ardent Tool Quick Reference]. FRU data, planar Type 1 vs Type 2, ECA history.
* IBM, ''IBM Personal System/2 Hardware Maintenance Manual'' (S52G-9971-02, October 1994). POST error code reference.

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